a) Field of the Invention
This invention relates to a scroll compressor used with air conditioners, refrigerators, etc.
b) Related Art
FIG. 15 is a longitudinal sectional view of a scroll compressor disclosed in Japanese Patent Laid-Open No. Sho 62-199986 (conventional example 1).
In the figure, numeral 1 is a fixed scroll formed on one face (lower side) with a plate-like spiral tooth 1a, and a bed plate of the fixed scroll has an outer peripheral surface formed like a cylindrical face. A boss part 1g shaped like a hollow circular cylinder is protruded upward on the opposite face to the plate-like spiral tooth 1a (upper side of the fixed scroll 1) and a groove for housing a seal member 10a separating a high pressure space 30 (spout side space) and a low pressure space 31 (suction side space) is formed in a portion opposite to the outer face of the boss part 1g.
Numeral 2 is an orbiting scroll formed on one face (upper side) with a plate-like spiral tooth 2a, and a boss part 2b receiving a drive force from a spindle 8 is projected on the opposite side (lower side).
Numeral 3 is a frame having an outer peripheral surface stuck to the inner face of a sealed vessel 9A and an upper end part 3a fixed to a separation plate 4. The frame 3 supports a thrust load of the orbiting scroll 2 and supports the spindle 8 radially.
The separation plate 4 is stuck to the inner face of the sealed vessel 9A above the frame 3, thereby basically separating the space in the vessel into the high pressure space 30 and the low pressure space 31. The fixed scroll 1 is restrained in radial and rotation directions by a pin 5 pressed into the separation plate 4.
Numeral 7 is an Oldham's coupling for restraining rotation of the orbiting scroll 2 and determining a phase between the orbiting scroll 2 and the frame 3.
Numeral 8 is a spindle coupled at the top end to the lower part of the orbiting scroll 2 and torque for driving the orbiting scroll 2 is given from a motor.
Next, the operation of the scroll compressor according to the conventional example 1 will be discussed.
First, an axial force that acts on the fixed scroll 1 will be described. An upward pushing force caused by gas pressure in a compression space acts on the lower face of the fixed scroll 1. On the other hand, high pressure acts on the top face of the boss part 1g of the fixed scroll 1, and a force produced by the high pressure presses the fixed scroll 1 downward, namely, against the orbiting scroll 2.
Next, a radial force that acts on the fixed scroll 1 will be described. A radial outward force mainly caused by gas pressure in the compression space acts on the plate-like spiral tooth 1a of the fixed scroll 1. The force is transmitted via the boss part 1g of the base plate of the fixed scroll 1 to the separation plate 4.
Next, a moment in the rotation direction that acts on the fixed scroll 1 will be described. A moment in the rotation direction mainly caused by gas pressure in the compression space acts on the fixed scroll 1 like the orbiting scroll 2. At the orbiting scroll 2, the moment is received by the Oldham's coupling 7; at the fixed scroll 1, it is received by means of the pin 5.
On the other hand, FIG. 16 is a longitudinal sectional view of a scroll compressor disclosed in Japanese Patent Laid-Open No. Sho 63-80088 (conventional example 2).
The structure and operation of conventional example 2 will be discussed with referenced to FIG. 16.
Parts identical with or similar to those previously described with reference to FIG. 15 are denoted by the same reference numerals in FIG. 16 and will not be discussed again. Numeral 1 is a fixed scroll and four bolt screw holes are made in the outer peripheral surface of a base plate of the fixed scroll 1. Numeral 12 is an elastic body typified by a plate spring, etc., which is formed with four bolt drill holes. Bolts are inserted into the two drill holes at both ends of the elastic body 12 for fixing the elastic body 12 to the end face on the outer peripheral surface spiral side of the fixed scroll 1. Also, bolts 15 are inserted into the two drill holes at the center of the elastic body 12 for fixing the elastic body 12 to the upper end face of a frame 3. Thus, the fixed scroll 1 and the frame 3 are elastically coupled axially by the elastic body 12, but basically are fixedly coupled in a radial direction and a rotation direction around the axis. In this connection, the elastic body 12 engages the end face on the anti-spiral side of the fixed scroll 1. The fixed scroll 1 integral with the frame 3 is backed into a sealed vessel 9A and fixed and supported by press fit, arc spot welding, etc.
Means for restraining an axial upward move of the fixed scroll 1 is a member stuck to the frame 3 by the bolts 15. A separation plate 4 is not positioned with respect to the frame 3 and is welded fully to the inner peripheral surface of the sealed vessel 9A.
FIG. 17 is a partially enlarged longitudinal sectional view to show the main part of the scroll compressor of the conventional example 2.
In the figure, numeral 10a is a seal member separating a high pressure space 30 (spout side) and an intermediate pressure chamber 4a and numeral 11a is a seal member separating the intermediate pressure chamber 4a and a low pressure space 31 (suction side); they are disposed to provide a minute gap between the fixed scroll 1 and the separation plate 4. The fixed scroll 1 is formed with a communication hole 1d for allowing a compression space on the side of a plate-like spiral tooth 1a to communicate with the intermediate pressure chamber 4a.
In the scroll compressor of convectional example 2, as described above, the fixed scroll 1 is supported on a shell main body 9 via the frame 3. The separation plate 4 is not supported on the fixed scroll 1 and is supported on the shell main body 9. Thus, the minute gap formed between the fixed scroll 1 and the separation plate 4 via the seal members 10a and 11a leans to one side on the entire opposite face because of welding distortion or deformation caused by full peripheral surface welding of the shell main body 9 and the separation plate 4, and variations in seal property, seal failure caused by uneven contact of the separation plate 4 and the fixed scroll 1, tooth tip contact, etc., occurs, which may cause variations in compressor performance, compressor performance failure, compressor reliability degradation, or compressor destruction.
The elastic body 12 such as a plate spring used to enable the fixed scroll 1 to axially move always receives a gas load and a moment acting on the fixed scroll 1 during the operation, thus fatigue failure, abnormal wear, etc., may occur.